The present invention relates to novel silicon carbide ceramics. Particularly, it relates to a toughened silicon carbide which is useful as structural materials.
A silicon carbide exhibits a high heat resistance, a high oxidation resistance and an excellent high-temperature strength, so that it is expected to be widely used as a heat-resistant structural material. However, a sintered silicon carbide is fragile (i.e. the toughness is low), so that it has only a low reliability as a structural material, which is the greatest barrier for the practical use of silicon carbide ceramics.
To overcome this disadvantage, it was reported in, for example, Journal of the American Ceramic Society, 67, 571 (1984) that titanium carbide particles are dispersed in silicon carbide matrix to thereby prevent the propagation of crack in a sintered body thus improving the toughness. However, the sintered materials obtained by this method has a structure where titanium carbide particles are only dispersed in silicon carbide matrix and exhibit a fracture toughness of at most 6MN/m.sup.3/2, so that they cannot be used without anxiety as a structural material which requires a high reliability.